What Is a COA for Peptides?
A COA (Certificate of Analysis) is a document issued by an analytical laboratory that verifies the identity, purity, and quality of a specific peptide batch. It typically includes HPLC (High-Performance Liquid Chromatography) results showing purity percentage and mass spectrometry (MS) data confirming the peptide’s molecular weight matches the target sequence.
What a COA Contains
HPLC purity: The most critical number. Shown as a percentage (e.g., 98.7%) representing the proportion of target peptide in the sample. Reputable suppliers deliver ≥98% purity. The COA includes the HPLC chromatogram — a graph showing peaks for the target peptide and any impurities.
Mass spectrometry: Confirms molecular identity. The observed molecular weight should match the theoretical weight of the target peptide sequence within ±1 Da (Dalton). This ensures you received the correct compound, not a different peptide at the same purity.
Additional data may include: batch/lot number, synthesis date, appearance (usually white lyophilized powder), solubility, net peptide content, sequence, and storage recommendations.
Why COAs Matter
Without a COA, you have no way to verify what you’re working with. Research results built on unverified peptides are unreproducible at best and dangerous at worst. A 2019 study analyzing peptides from online suppliers found significant discrepancies between advertised and actual purity in products without third-party COAs (PMID: 30816438).
Red Flags
Be wary of: COAs without a specific lot number, missing chromatograms (just a number without the graph), COAs that look identical across different peptides or batches, and suppliers who refuse to provide COAs upon request. Every reputable supplier provides batch-specific COAs.
Related Resources
- How to Read a Peptide COA: Complete Guide
- Research-Grade vs Pharmaceutical-Grade Peptides
- Browse NorthPeptide Products (COAs Available)
Written by NorthPeptide Research Team · For laboratory and research use only. Not for human consumption.
Written by NorthPeptide Research Team
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